Treatment of blood



Patented May 5, 1942 TREATMENT or BLOOD Ivan A. Parientjev, Nyack, N.Y., assignor to Lederle Laboratories, Inc., New York, N. Y., a

corporation of Delaware No Drawing. Application October 21, 1939, SerialNo. 300,594

1 Claim.

This invention relates to methods for obtaining plasma from the blood ofimmune animals.

In the production of antitoxins and the like, the customary procedureentails the bleeding of immunized animals such as horses, pigs, rabbits,etc. To obtain plasma, the blood is led into a receptacle containing asuitable anticoagulant which maintains the fibrin in solution. The blooddoes not coagulate but the blood cells (erythrocytes) settle to thebottom of the receptacle and transparent plasma collects in a layer overthe blood cells. The supernatant plasma layer may be siphoned oil andtreated as desired. However, the settled blood cells do not pack veryfirmly and a considerable amount of plasma remains between the bloodcells and is diificult to recover.

By washing the blood cells with salt solution, after removing thesupernatant layer of plasma, considerably more plasma 'can be obtained.By this procedure, a considerable increase in the yield of plasma can beachieved. However, this method of processing the blood cells presentsdif- 'ficulties in that the suspension of the cells in saline is suchthat the cells do not settle out from the liquid. Therefore, in order toseparate the cells from the liquid, a basket centrifuge or a creamseparator must be used. The use of either of these types of apparatus isobjectionable in that the centrifuge requires considerable time andlabor and while the cream separator is more rapid than the centrifuge,the action of the separator is such as to break down the erythrocytesand the liquid is more or less hemolyzed. Furthermore, both types ofapparatus are very expensive and the elimination thereof is highly to bedesired.

I have discovered that the addition of small amounts of gums to thesaline used for washing the blood cells causes the blood cells to settledown into a compact mass and by this means the plasma diluted with thesalt solution forms a supernatant layer which can be siphoned'off fromthe settled down blood cells. Gum tragacanth is especially convenientfor this use since it is effective in very small amounts.

As a typical washing liquid I may dissolve 136 grams of sodium chlorideand 80 grams of sodium pyrophosphate in 15.5 liters of distilled water.This solution is adjusted to pH 7.0 by addition of 6.8 cc. phosphoricacid (sp. gr. 1.7). r

The resulting solution is made up to 16 liters by the addition ofsuflicient distilled water. There is then added to thesolution 48 gramspowdered gum tragacanth (0.3%) and the mixture is agitated vigorously tomoisten all of the gum. The solution is sterilized in an autoclave forthirty minutes and is then ready for use.

To use this solution, there is added to the blood cells with theirassociated plasma, after the supernant plasma is siphoned off in theusual man .ner, an equal volume of the washing solution.

After standing about twenty-four hours, preferably in a cold room, it isfound that the blood cells have settled to the bottom of the liquid inthe form of a compact mass from which the sucreased quantities aregenerally not necessary.

In place of the gum tragacanth, I may use 0.5% to 1.0% gum acacia, gumarabic and similar gums. Mixtures of the gums may also be used.

The use of the gums for facilitating sedimentation of the'blood cells iseffective with the usual types of anticoagulants such as the'sodium andpotassium oxalates, citrates, etc. The gum is especially valuable whensodium pyrophosphate is utilized as the anticoagulant as described in myapplication Serial No. 300,595 filed October 21, 1939. The use of sodiumpyrophosphate prevents the cells from becoming as fragile and as easilybroken as is the case when oxalates or citrates are used as theanticoagulants.

In washing the blood cells, the washing liquid is preferably an isotonicor hype'rtonic salt solution which should be neutral or slightlyalkaline, e. g. about pH 7-7.5. In addition, the washing solution shouldcontain a small amount of an anticoagulant, such as the pyrophosphate inthe specific example described.

As will be seen from the above, the use of the gums in washing theplasma from the blood cells avoids the necessity of using expensiveapparatus and, at the same time, prevents hemolysis to give a usable,diluted plasma which represents an increase from 10% to 30% in theyields of plasma as compared with a process which does not involve thewashing treatment.

It will be obvious that my process is subject to minor changes andvariations other than those described without departing from the spiritand scope thereof.

I claim:

A process of obtaining increased yields of plasma from blood whichcomprises mixing blood with an anticoagulant, permitting the blood cellsto settle, separating the supernatant plasma from the settled bloodcells and. associated plasma, mixing the blood cells and associatedplasma with a substantially neutral sodium chloride solution containingan anticoagulant and not more than 0.2% of gum tragacanth, allowing themixture to stand in the cold until the blood cells settle to a compactmass and removing the diluted plasma from the settled blood cells.

IVAN A. PARFENTJEV.

